Disclosed herein are ultra-violet curable gellant inks for tactile and regular print applications, in specific embodiments as security features for signature and document authentication. Also described is a method for forming signature and document authentication security features with the described ultra-violet curable gellant inks.
Document authentication is an increasingly important issue, such as for agencies, including government organizations that frequently issue secure documentation. For example, Ontario Driver's Licenses have recently employed raised text signatures, birthdates, and license numbers for security purposes. See, for example, http://news.therecord.com/News/CanadaWorld/article/279991.
With the general availability of high quality color reproduction, distinguishing an original from a copy and verifying, for example, a signature, on the original has become more difficult. More specifically, digital printers, scanners, and image editing software have made it possible for copies of legitimate documents to be made that are difficult to distinguish from the original.
One conventional approach to authenticating documents is the use of machine readable encoded data which is rendered onto a document or other physical media along with other information.
For example, authenticating information can be encoded into thousands of tiny, individual glyph elements. Each element consists of a small 45 degree diagonal line, as short as 1/100th of an inch or less, depending on the resolution of the printing and scanning that is used. Each glyph represents either binary 0 or binary 1, depending on whether the glyph slopes to the left or right. Sequences of glyphs can be used to encode numeric, textual, or other information. The glyphs are grouped together on the page, where the glyphs form unobtrusive, evenly textured gray areas, similar to a half-toned picture.
Another conventional approach to the problem of verifying document authenticity is the use of authenticating information embedded in a print, for example, a seal or a date and time. The embedded authenticating information catches the light when the print is tilted and can be seen as an additional and separate image. Moreover, watermarks, conventionally, have also been used to authenticate a document.
These various conventional methods of verifying a document share the feature that it is very difficult to reproduce the authenticating feature of the original on a conventional copier or scanner. Therefore, a copy of the original can be distinguished from the original.
However, the conventional methods of verifying a document have drawbacks. For example, glyphs need a device to decode the authenticating information. Moreover, conventional watermarks need a proper source of light to discern the authenticating information. In these various conventional methods, outside intervention; e.g., from either a machine (optical reader) or a light source; is needed to detect or discern the authenticating information.
Commonly assigned, co-pending U.S. patent application of Peter M. Kazmaier, Hadi K. Mahabadi, Paul F. Smith, Chris A. Wagner, Gabriel Iftime, and Tyler B. Norsten, Ser. No. 11/613,759, entitled “Tactile Security Feature for Document and Signature Authentication,” filed Dec. 20, 2006, which is hereby incorporated by reference herein in its entirety, describes, in embodiments, a system and method create an authentication mark on a recording medium by depositing marking material on a medium in an image area to create a marking material image and to create a marking material authentication image. A predetermined amount of additional marking material is further deposited upon the medium in the authentication image area to increase an amount of marking material associated with the marking material authentication image in the authentication image area. The fixed marking material associated with the authentication image area is a tactilely perceptible authentication mark wherein the fixed marking material associated with the authentication mark has a height, with respect to a surface of the medium that is tactilely perceptible.
U.S. Pat. No. 6,644,763 describes a method for creating raised and special printing effects using ink jet technology. The method includes the steps of depositing a light curable photo-polymer material on the area selected for the printing effects, and curing the area. The amount of material to be deposited corresponds to the area selected for the printing effects and the height of the raised area relative to the medium on which the photo-polymer material is deposited. See the Abstract.
U.S. Pat. No. 5,627,578 describes a method and device for raised letter or graphics printing, by means of a sprayed wet ink deposition on a print recording medium. Subsequent dispensing of thermographic powder thereon, with adherence of the powder only to the wet ink, followed by heating to a fixing temperature of the powder, results in the raised lettering or graphics. A standard portable ink jet printer of the bubble jet type, controlled, with graphics software control, by a personal computer, provides the requisite non-contacting ink deposition. The dispensing cartridges of the ink jet printer are provided with non-contact-drying ink formulations (with two or more separate colors, if desired) for the portion of graphics or printing which is to be in raised form. A thermographic powder dispenser and heating member is connected to the output of the ink jet printer, or integrated therewith for completion of the raised printing process. Raised and non-raised printing is also possible by use of separately dispensed drying and non-drying inks. See the Abstract.
Ink jet printing devices are known in the art. For example, ink jet printing devices are generally of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through at least one orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break-up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field that adjusts the trajectory of each droplet in order to direct it to a gutter for recirculation or a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice directly to a position on a recording medium in accordance with digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium. There are generally three types of drop-on-demand ink jet systems. One type of drop-on-demand system is a piezoelectric device that has as its major components an ink filled channel or passageway having a nozzle on one end and a piezoelectric transducer near the other end to produce pressure pulses. Another type of drop-on-demand system is known as acoustic ink printing. As is known, an acoustic beam exerts a radiation pressure against objects upon which it impinges. Thus, when an acoustic beam impinges on a free surface (that is, liquid/air interface) of a pool of liquid from beneath, the radiation pressure which it exerts against the surface of the pool may reach a sufficiently high level to release individual droplets of liquid from the pool, despite the restraining force of surface tension. Focusing the beam on or near the surface of the pool intensifies the radiation pressure it exerts for a given amount of input power. Still another type of drop-on-demand system is known as thermal ink jet, or bubble jet, and produces high velocity droplets. The major components of this type of drop-on-demand system are an ink filled channel having a nozzle on one end and a heat generating resistor near the nozzle. Printing signals representing digital information originate an electric current pulse in a resistive layer within each ink passageway near the orifice or nozzle, causing the ink vehicle (usually water) in the immediate vicinity to vaporize almost instantaneously and create a bubble. The ink at the orifice is forced out as a propelled droplet as the bubble expands.
In a typical design of a piezoelectric ink jet device, the image is applied by jetting appropriately colored inks during four to eighteen rotations (incremental movements) of a recording medium, such as an image receiving member or intermediate transfer member, with respect to the ink jetting head. That is, there is a small translation of the print head with respect to the recording medium in between each rotation. This approach simplifies the print head design, and the small movements ensure good droplet registration. At the jet operating temperature, droplets of liquid ink are ejected from the printing device. When the ink droplets contact the surface of the recording medium, they quickly solidify to form a predetermined pattern of solidified ink drops.
Ink jet printing processes may employ inks that are solid at room temperature and liquid at elevated temperatures. Such inks may be referred to as solid inks, hot melt inks, phase change inks and the like. For example, U.S. Pat. No. 4,490,731, the disclosure of which is totally incorporated herein by reference, discloses an apparatus for dispensing solid ink for printing on a recording medium such as paper. In thermal ink jet printing processes employing hot melt inks, the solid ink is melted by the heater in the printing apparatus and utilized (jetted) as a liquid in a manner similar to that of conventional thermal ink jet printing. Upon contact with the printing recording medium, the molten ink solidifies rapidly, enabling the colorant to substantially remain on the surface of the recording medium instead of being carried into the recording medium (for example, paper) by capillary action, thereby enabling higher print density than is generally obtained with liquid inks. Advantages of a phase change ink in ink jet printing are thus elimination of potential spillage of the ink during handling, a wide range of print density and quality, minimal paper cockle or distortion, and enablement of indefinite periods of nonprinting without the danger of nozzle clogging, even without capping the nozzles.
The use of ink jet printers in forming raised printed images is also known, for example, as indicated in U.S. Pat. Nos. 6,644,763 and 5,627,578 above. However, these printers for forming raised images are typically dedicated machines designed and used solely for raised print applications, such as forming Braille images. Where a user requires only a certain portion of print jobs to be done utilizing raised print, it can be costly for the user to have two print devices, one strictly for the raised print jobs.
In general, phase change inks (sometimes referred to as “hot melt inks”) are in the solid phase at ambient temperature, but exist in the liquid phase at the elevated operating temperature of an ink jet printing device. At the jet operating temperature, droplets of liquid ink are ejected from the printing device and, when the ink droplets contact the surface of the recording medium, either directly or via an intermediate heated transfer belt or drum, they quickly solidify to form a predetermined pattern of solidified ink drops.
Phase change inks for color printing typically comprise a phase change ink carrier composition which is combined with a phase change ink compatible colorant. In a specific embodiment, a series of colored phase change inks can be formed by combining ink carrier compositions with compatible subtractive primary colorants. The subtractive primary colored phase change inks can comprise four component dyes or pigments, namely, cyan, magenta, yellow and black, although the inks are not limited to these four colors. These subtractive primary colored inks can be formed by using a single dye or pigment or a mixture of dyes or pigments. For example, magenta can be obtained by using a mixture of Solvent Red Dyes or a composite black can be obtained by mixing several dyes. U.S. Pat. No. 4,889,560, U.S. Pat. No. 4,889,761, and U.S. Pat. No. 5,372,852, the disclosures of each of which are totally incorporated herein by reference, teach that the subtractive primary colorants employed can comprise dyes from the classes of Color Index (C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and Basic Dyes. The colorants can also include pigments, as disclosed in, for example, U.S. Pat. No. 5,221,335, the disclosure of which is totally incorporated herein by reference. U.S. Pat. No. 5,621,022, the disclosure of which is totally incorporated herein by reference, discloses the use of a specific class of polymeric dyes in phase change ink compositions.
Phase change inks have also been used for applications such as postal marking, industrial marking, and labeling.
Phase change inks are desirable for ink jet printers because they remain in a solid phase at room temperature during shipping, long term storage, and the like. In addition, the problems associated with nozzle clogging as a result of ink evaporation with liquid ink jet inks are largely eliminated, thereby improving the reliability of the ink jet printing. Further, in phase change ink jet printers wherein the ink droplets are applied directly onto the final recording medium (for example, paper, transparency material, and the like), the droplets solidify immediately upon contact with the recording medium, so that migration of ink along the printing medium is prevented and dot quality is improved.
While known compositions and processes are suitable for their intended purposes, a need remains for a method that enables authentication of an original document without the utilization of outside intervention; e.g. from either a machine (optical reader) or a light source. Moreover, it is desirable to provide a method that enables authentication of an original document through tactile perception. Furthermore, it is desirable to provide a method that enables authentication of an original document through tactile perception while preventing the authenticating information of the original document from being reproduced using conventional scanners and printers. Further, a need remains for a robust marking material compatible with a printing device that can produce regular text and tactile security features.
The appropriate components and process aspects of the each of the foregoing U.S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof.